Reaction chamber for monopropellant or bipropellant fuels



E. B. zwlcK 2,999,358 REACTION CHAMBER RoR MoNoRRoRELLANT 0R BIPROPELLANT FUELS sept. 12, 1961 Filed Oct. 2l, 1957 lllhwfffrrrfr ...A

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` 'M2M/ 7 V United States Patent O 'l' 2,999,358 REACTION CHAMBER FR MON OPROPELLANT R BIPROPEL'LANT FUELS Eugene B. Zwick, Pacoima, Calif., assignor, by mesne assifgnnrents, to Sundstrand Corporation, a corporation o 01s Filed Oct. 21, 1957, Ser. No. 691,301 '6 Claims. (Cl. 60--39.46)

This invention relates to a reaction chamber for monopropellant fuels, such as ethylene oxide, nitromethane, a mixture of -nitromethane and nitroethane and similar monopropellant fuels, or bipropellant fuels, such as liquid or gaseous hydrocarbons reacting with some oxidizer.

The invention will be disclosed as a device for decomposition of monopropellant fuels, but it can be adapted for use with the bipropellant mixtures as will be pointed out at the end of this specification.

It is an object of this invention to provide a homogeneous reaction chamber in which a monopropellant fuel is injected into the chamber in a liquid form as a nely divided spray and this spray is continuously and rapidly mixed with the products of reaction for producing a nearly homogeneous mixture of burning fuel and hot gas throughout the volume of the chamber.

It is an additional object of this invention to provide a reaction chamber in which mixing and rapid heating and ignition of fuel is produced by injecting fuel in a form of a :line spray and directing the ow of hot gases in the direction opposite to the direction of ow of the injected fuel, the hot gases completely surrounding and being mixed with the injected fuel immediately upon its entry into the combustion chamber, for producing rapid heating, ignition, and reaction of the fuel.

It is also an object of this invention to provide a homogeneous reactor of the above type which has a spherical, centrally located reaction chamber and first and second concentrically mountedand spaced from each other metallic spheres surrounding the central spherical chamber, the first sphere being adjacent to and spaced from the inner sphere, the central and the rst sphere defining a spherical duct for conveying the burned fuel to an outgoing duct, While the first and the second spheres provide a gas-filled insulation jacket for the reaction chamber.

The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawing in which a single embodiment of the invention is illustrated by way of an example. It is to be expressly understood, however, that the drawing is for the purpose of illustration and description only, and is not intended as a definition of the limits of the invention.

Referring to the drawing:

FIGURE 1 is a perspective view of the chamber and FIGURE. 2 is a sectional view of the chamber illustrated in FIGURE l.

Referring to the drawing, the chamber comprises two hemispherical outer shell members 10 and 12, provided with anges 13 and 14. The two hemispheres 10 and 12 of the chamber are held together by means of a plurality of bolts 16 and in order to obtain a gas-tight joint between the two anges, they are provided with two ange rings 17 and 1S. The ange rings 17 and 18 and flanges 13 and 14 are provided with recesses which are used for accomodating three gaskets '19, 20 and 21 made of heat-resisting material, such as asbestos, or asbestos impregnated with tallow or silicons.

2,999,358 Patented Sept. 12, 1961 The outer shell 10-12 preferably is made of stainless steel which is also the metal used for an intermediate shell 22 and an inner shell 24. The ange rings 17 and 18 extend into the inner chamber, as indicated in FIGURE 2, and are provided with circular seats for mounting the inner shell, composed of two hemispherical members 24a and 24b, and the intermediate shell, composed of -two hemispherical members 22a and 22h, in concentric relationship with respect to the outer shell 10. The outer shell is also provided with two locating pins 26 and 27 which are used for proper positioning of the hemispherical members with respect to each other, so that the vents, or the orices, provided in these members are aligned in proper manner with respect to each other, as shown in FIGURE 2. The outer and the intermediate shells are provided with two aligned openings for accomodating an outgoing duct 25 which includes a boss 1-1 welded to the outer hemisphere 10. This boss is provided with a funnel-shaped oriiice 28 which opens into the space surrounded by the intermediate and the inner shells 22 and 24. This space is used as a spherical duct for conveying the products of decomposition reaction to an outgoing duct 25. A DeLaval nozzle 30 is connected to duct 25. The DeLaval nozzle is connected to tube 29 and boss 11 by means of threaded joints, including nuts 31, 32 and 33 and sealing members illustrated in FIGURE 2. The DeLaval nozzle is used in the exhaust duct for obtaining proper pressure in the reaction chamber, the throat of the nozzle being proportioned so as to introduce suicient resistance to ow of gases for creating that pressure Within the reaction chamber which is required for obtaining the proper rate and type of burning desired in the chamber.

The f-uel is introduced into the chamber by means of a plurality of nozzles 35 through 40 which are distributed at random on the two hemispheres. Although a symmetrical distribution or" the nozzles may also be used, the random distributionis the preferred mounting of these nozzles for obtaining a thorough mixing of the sprayed fuel and of the products of the reaction immediately upon the entry of the sprayed fuel into the inner chamber. In order to insure rapid heating, igniting, reaction and burning of the sprayed fuel within this chamber is provided with orifices 41, 42, 43, 44, etc., (there are six orifices in the illustrated configuration of the chamber only four being Visible in FIGURE 2) these orifices being axially aligned with the respective longitudinal axis of the respective nozzles. The diameterY of these orices is made larger than the diameter of the tips of the spray nozzles, these tips terminating in the respective planes of the orifices, so as to provide sul'lcient exits, or exhaust ports, for the exhaust gases. These hot gases flow from the central chamber into the spherical duct formed by the inner sphere 24 and the intermediate sphere 22. Accordingly, the fuel is injected into the chamber 47 by the nozzles 3S through 40 where heating, ignition, decomposition and burning of the fuel takes place. Mixing of the injected fuel with the burning mixture takes place immediately upon the injection of the fuel into the inner chamber 47. The hot gases then leave chamber 47 through the orifices 41, 42, 43, etc., and flow through the spherical duct 48 and then into the outgoing duct 29 through the DeLaval nozzle.

The hemispherical members 24a and 24b are kept at high temperature because they are surrounded by hot gases on both sides.

In order to minimize the heat loss as much as possible, and to provide a hot surface for promoting the combustion processes, the chamber is also provided with the intermediate spherical member 22 which is mounted in space relationship with respect to the outer shell lil- 12. While the outer shell 10-12 must be suiciently strong to withstand the maximum pressure obtainable within the charnber, the inner spheres 22 and 24 are made of thin stainless steel sheet metal since the pressure of gases is the same on both sides of these members. r[he intermediate sheet 22 is provided with six orifices, such as oriiiceV 50, which permit the free now of gases from duct 43 into the space between the outer shell 1G and the intermediate shell l22. These orifices are also used to permit the insertion-of the nozzles into the chamber 47 through spherical shell 22.

'Ihe chamber is also provided with an electric heating element 55 which is connected to a source of electric energy by means of a concentric cable 56 having an'inner conductor 57 and an outer conductor S8. The heating element is preheated to a sufficiently high temperature so as to initiate the exothermic reaction.

The chamber is also provided with a tube 60 which is mounted on a boss 61 on the outer shell 12 and can be inserted into the central sphere or into the space between the two inner spheres. This tube serves two purposes. It may be used as a pressure tap for monitoring the pressure within the combustion chamber, or, alternatively, it may be connected to lthe exhaust from an auxiliary reaction chamber. In this latter application the auxiliary chamber is used to supply heated gas to the reaction chamber 47 in order to pre-heat the inner surfaces of the chamberfo-r the initiation of the combustion reaction. Initiation of the combustion reaction may thus be accomplished by use of either the electrical heating element 55, the exhaust from an auxiliary chamber admitted through tube 66, or by the use of both of these preheating devices in combination. A temperature measuring element 65 is mounted on a boss 66 attached to the outer shell 12, and protrudes into the central sphere. This temperature measuring element is used to determine the internal temperature ofthe reaction chamber. When this temperature has risen sufliciently so as to permit the initiation of the reaction, the Ifuel is admitted through the plurality of nozzles 35 through 40. Once the reaction has been initiated, operation of the pre-heating devices (heating element 55 and/or exhaust products from the auxiliary chamber admitted through tube 60) is discontinued and the reaction is henceforth selfsustaining.

The advantages of the disclosed chamber are: creation 'of the reaction throughout the inner volume 47 yand the chamber because of the continuous intermixing of the injected fuel with hot gases; reaction chamber 47 has 10W heat loses because duct 43 and space 62 eiectiveliy nsulate the inner chamber from the outer wall since the entire volume 47 of the inner chamber is utilized for producing the exothermic reaction, the reactor has a small Vc/At ratio which is the ratio of the volume of the cham,- ber (Vc in this case corresponds to volumes 47 and 48 contained within shell 22 and At is the minimum crosssectional area, or Through Area, of nozzle 30. The above ratio Vc/A, is also known as the L* (L-star) ratio. Low L* ratio is obtained with this chamber because of the utilization of the entire volume 47 for producing the reaction due to the eflicient mixing of the propellant with the products of reaction within the core of this volume, because the surface of shell 24 kept hot by the flow of hot gases on both sides of this shell, and because of the intermixing of the incoming spray of fuel with hot gases achieved by making the sprayed fuel flow in `one direction and the hotgases in thepopposite direction directly in the vicinity of the sprayed fuel through the oriices 41, 42, etc., which completely surround the hemisphecrical tips of the nozzles.

The disclosed chamber can also be used with bipropellaut fuel systems. In this case the nozzles may be (a) premixing injection nozzles (b) bipropellant injection nozzlers, or (c) single propellant injection nozzles.

In (a), the fuel and the oxidizers are mixed in thebody of the nozzle and injected in the pre-mixed state. In (b),

each nozzle is designed with two or more orifices through i which the two components of the bipropellant system are injected, with mixing, occurring after injection. In (c) somel of the nozzles are used to inject the fuel while the remainder are used to inject'the oxidizer.

Preheating of the injected bipropellant fuels is accomplished as effectively in 'the three cases cited above as it is in the case of a monopropellaiit fuel. In each case the incoming fuels 'are' heated :byv the" hot exhaust gases which pass yaround the injected streams -as these `gases flow to- -Ward the exhaust'oriiices.l n

Since the disclosed chamber may be used with monopropellant or bipro'pellant fuels, the word fuel, as used in the claims, applies to the monoprop'ellant as well as the bipropellant fuels. In the latter case the mixture, strictly speaking, consists of the lfuel per se and the oxidizer. For

`lack of a better term, the word fuel is used in a generic spherical shell, an intermediate metallic spherical shell, an inner metallic spherical shell, means for supporting said intermediate and said inner shells Within and in spaced and concentric relationship with respect to the outer shell, said inner shell being ixediy. held by said means in spaced relationship with respect to the intermediate shell, the outer surface of said inner shell and the inner surface of said intermediate shell forming a spherical exhaust duct, said intermediate shell being also held by said means in spaced relationship with respect to said outer shell, the space between the intermediate shell and the outer shell providing a gas-filled insulation jacket for said inner shell, a plurality of injection nozzles randomly distributed around the outer shell, said nozzles injecting fuel 4in the form of a iine spray into the inner shell, a plurality of unrestricted orifices provided in said inner shell, said orifices being of greater diameter than the tips of said nozzles,-said orifices lbeing in concentric relationship with respect to the respective nozzles, and an exhaust duct connected to said spherical duct through said intermediate shell for conveying the products of reaction from said inner shell through said orifices and through said spherical duct and into said exhaust duct.

2. A reaction chamber comprising outer, intermediate and inner metallic spherical shells; means for supporting said intermediate shell within and in spaced and concentric relationhip with respect to the outer,` shell; said means also supporting said inner shell within and in spaced and concentric relationship with respect to said intermediate shell; the outer surface of said inner shell and the innerrsurface of said intermediate shell dening a spherical exhaust duct; the space 'between the interme- 'diate `shell and the outer shell providing a gas-lled insulation jacket for said intermediate and inner shells; a plurality of injection nozzles randomly distributed around the outer shell; said nozzles having injection tips for injecting fuel as a line spray into the inner shell; a plurality of `unrestricted orifices, or ports, provided in said inner shell, each of said ports having -a greater diameter than the diameter `of the adjoining nozzle tip, said ports being laligneld with the respective nozzles; and an exhaust tube connected to said outer and intermediate shells for conveying the products of reaction from said inner chamber to said exhaust tube through said ports, said spherical exhaust duct, and past said injection tips;

3. A reaction chamber, said chamber comprising an inner shell, the inner space bound =by said inner shell constituting the reaction space of said chamber, a second shell surrounding and being in spaced yand concentric relationship with respect to said inner shell, the space between the two shells constituting a spherically shaped exhaust duct, an exhaust tube connected to said second shell for conveying gases from said reaction space through said exhaust duct, a plurality of injection nozzlesrandomly distributed around said secondJ shell, Veach of said nozzles beingpositioned to inject fuel as a spray directed toward the center of said reaction space, and a corresponding plurality of unrestricted orifices in said inner shell, said orifices having a larger diameter than the tip portions of the respective nozzles, each nozzle and its orice having a common longitudinal axis, said fuel, after being converted into hot gases, leaving said reaction space through said orices, and past said nozzles, in the directions opposite to the directions of the respective sprays.

4. The reaction chamber as dened in claim 3 which also includes `an electrically heated heater element centrally mounted in said inner shell.

5. The reaction chamber as detned in claim 3 which also includes a third outer shell surrounding said second shell, said third shell being concentric and in spaced relationship with respect to said second shell, the space between the second and the third shell constituting a gasiilled `insulation medium for said inner and second shells.

6. A reaction chamber comprising an outermetallic spherical shell, an intermediate metallic spherical shell, an inner metallic spherical shell, means for supporting said intermediate yand said inner shells within and in spaced and concentric relationship with respect to the outer shell, said inner shell being xedly held by said means in spaced relationship with respect to the intermediate shell, the outer surface of said inner shell and References Cited in the le of this patent UNITED STATES PATENTS 1,294,120 Lang Feb. 11, 1919 2,555,080 Goddard May 29, 1951 2,655,205 Linderoth Oct. 13, 1953 2,709,887 Goddard `lune 7, 1955 2,711,075 Perret June 21, 1955 2,827,759 Bruckmann Mar. 25, 1958 FOREIGN PATENTS 1,096,378 France Ian. 26, 1955 619,251 Great Britain Mar. 7, 1949 135,570 Switzerland Dec. 2, 1929 

